The research and development of the coronavirus disease 2019 (COVID-19) vaccine is being carried out globally. Although vaccine research and development technology has made great progress, the possibility of obtaining a safe and effective vaccine that can control the global epidemic in a short period of time is still low due to the antibody-dependent enhancement effect (ADE) of the vaccine and the mutation of the virus. In the absence of specific treatment for COVID-19, finding other alternative protection schemes has become another treatment idea. Epidemiological studies have found that, in this COVID-19 epidemic, countries with long-term Bacillus Calmette-Guerin (BCG) vaccination policies have relatively less cases and lower mortality rates than countries without relevant policies. This phenomenon may be related to the "training immunity" effect of BCG. https://www.selleckchem.com/products/tradipitant.html In order to further clarify the preventive and protective effects of BCG vaccine on SARS-CoV-2 infection, a number of clinical trials are underway.Objective To construct and verify camelidae natural nanobody phage display library for selection of nanobodies against various antigens, and to obtain and identify the nanobody targeting CD19. Methods The total RNA of spleen of Bactrian camel was reverse transcribed and the variable region gene fragment of its heavy chain was obtained by nested PCR. It was constructed into the pCANTAB5e phagemid vector and electrotransformed into TG1 E. coli to develop the natural nanobody phage display library. After rescued by the KM13 helper phage, its capacity and diversity were analyzed and identified. Nanobody against CD19 was screened using biotinylated antigen combined with streptavidin magnetic beads, followed by ELISA, sequencing, exogenous expression and verification. Results The constructed natural phage nanobody display library had great diversity, and its fragment insertion rate was about 100%. The amino acid homology of 20 randomly selected clones was 65.85%, and the titer of the display library rescued by the helper phage was 9.0×1013 CFU/mL. After panning with CD19 as the antigen, the positive clones were sequenced and analyzed, and finally anti-CD19 nanobody sequences were obtained. The exogenously expressed anti-CD19 nanobody based on the sequences was verified having the ability to bind to CD19. Conclusion A camelidae natural nanobody phage display library with high titer and great diversity has been successfully constructed. Three anti-CD19 nanobody sequences have been obtained by panning with CD19. In addition, this study provides technical support for researching and developing diagnostic kits and antibody drugs targeting CD19, and it is a novel direction to improve CAR-T cells targeting CD19.Objective To observe the relationship of rheumatoid arthritis (RA) bone destruction with T cells, regulatory T cells (Tregs), CD19+ B cells and immune inflammation. Methods The study enrolled randomly 20 RA patients (RA group) and 20 normal controls (NC group). Bone mineral density was measured by DXEA dual energy X-ray bone densitometer. The serum levels of γ-interferon (IFN-γ) of Th1 cells, interleukin-4 (IL-4) of Th2 cells, IL-17, type I procollagen amino terminal propeptide (PINP), type I collagen carboxy terminal peptide (CTx), receptor activator of NF-κB ligand (RANKL) and osteoprotectin (OPG) were detected by ELISA. T-cell subsets, Tregs, CD19+ B cells in peripheral blood were measured by flow cytometry. Spearman method was used to analyze the correlations of T cells, Treg and CD19+ B cells with bone density and Th1 and Th2 cytokines. Results The bone mineral density T value of the RA group was lower than that of the NC group. The bone mineral density T value of the double forearm was lower than that of the lumbar spine in the RA group. Compared with the NC group, the expression of IFN-γ, IL-17, Th1/Th2 cells, CTx, RANKL increased, and IL-4, PINP decreased in the RA group. Compared with the NC group, the expression of CD4+/CD8+ T cells, CD19+ B cells increased, and CD8+ T cells, CD4+CD25+ Tregs decreased in the RA group. Correlation analysis showed that CD8+ T cells were positively correlated with Th1/Th2 cells and IL-17, while CD4+ CD25+ Tregs were negatively correlated with CTx, and CD19+ B cells were negatively correlated with OPG in RA. Conclusion T cells and CD19+ B cells may participate in the process of bone destruction in RA by mediating inflammatory immunity.Objective To investigate the regulation and clinical significance of T cell immunoglobulin and mucin domain-containing molecule 3 (TIM-3)/galectin-9 signaling pathway in regulatory T cells (Tregs) and Th17 cells in patients with chronic lymphocytic leukemia (CLL). Methods The study enrolled 36 healthy individuals and 40 newly diagnosed CLL patients. The Tregs, Th17 cells, TIM-3+ Tregs and TIM-3+ Th17 cells were detected by the flow cytometry in their peripheral blood. Concentrations of IL-10, IL-17 and galectin-9 in serum were measured by the ELISA. Results Compared with the healthy controls, the CLL group had the higher levels of TIM-3+ Tregs, Tregs/Th17 cell ratio, TIM-3+ Tregs/TIM-3+ Th17 cell ratio, IL-10, galectin-9, and IL-10/IL-17 ratio. The level of TIM-3 expression on T cells, galectin-9 and the IL-10/IL-17 ratio in the CLL patients increased with the advance of Binet stage. Conclusion The TIM-3/galectin-9 signaling pathway is involved in the negative regulation of T cells in patients with CLL.Objective To investigate the expression and clinical significance of phosphatase and tension homolog deleted on chromosome ten (PTEN) and stimulator of interferon genes (STING) in human tongue squamous cell carcinoma (TSCC). Methods The expression of PTEN and STING protein in 65 pairs of TSCC and paracancerous tissues was detected by immunohistochemical EnVision method, and the relationships between PTEN, STING and clinicopathological parameters, overall survival (OS) and prognosis were analyzed by statistical methods. Results Compared with the adjacent tissues, the expression of PTEN in TSCC significantly decreased, and the expression of STING significantly increased. PTEN was negatively correlated with STING. In TSCC, the expression of PTEN and STING were correlated with pathological grade, TNM stage and lymph node metastasis. There were no significant correlations between the expression intensity of PTEN, STING and the gender and age of patients. The low expression of PTEN and the high expression of STING in TSCC tissues were significantly associated with poor prognosis and significantly shortened overall survival of patients.